Page 365 - Engineered Interfaces in Fiber Reinforced Composites

346 Engineered interfaces in jiber reinforced composites

18 1

~16-
n
!2- - without interleaves
g14 - --- with inter leaves
d-
-
2 12
4- L
v)
d
2 10-
L
0
z -
8-
-
(b) Distance from free edge
- 6
20 16 12 8 4 0
(a) Distance from free edge
Fig. 8.14. Normalized interlaminar (a) normal stress, uJ~, and (b) shear stress, T,.=/cc,, along the interface
between the 90" ply and its adjacent ply of a [ f 30"2/90"~/-30"2/ + 30°& carbon fiber-epoxy matrix
laminate. Chan et al. (1986).

film is sufficiently thick. Table 8.4 presents a compilation of data on the improvement
of interlaminar fracture toughness with relation to the adhesive film thickness.
Fig. 8.16 illustrates schematically the different configurations of interleaving strips
which have been studied (Chan et al., 1986; Chan and Ochoa, 1989; Kim, 1983):
(1) Adhesive strips interleaved along the free edge.

1000,
0 ultimate failure ICJ delamination
800
3
$. 600
6
m
C 400
Q)
L
tj
200

Fig. 8.1 5. Edge delamination and ultimate strength of [ i 35"/Oo/9O0], AS4 carbon fiber-3501 epoxy matrix
composite laminates with and without interleaves.